If you need to delete a calendar connected to other calendars, it only takes a few clicks to do so.
First, open your Calendar account and go to settings. You can find the settings "wheel" on the left side of your screen toward the bottom.
Once you open the Settings menu, choose "Calendars" listed under "Availability" from the menu.
Once you open this up, you will see your Availability Calendars as well as you Other Calendars.
Look for the calendar that you want to remove. Once you have located it, you will see an "X" on the right side of the screen. Clicking on the "X" will delete that calendar from being linked to your Calendar account.